With the two candidates in the top two slots in both states, it’s looking less likely that another candidate can coalesce enough support to challenge Mr. Romney. And there’s little doubt about who would win in a Romney-Paul matchup, political science experts say.

“Romney would be thrilled if Ron Paul emerged as his major opposition.... Paul has a sturdy floor of backers, but also a low ceiling, beyond which he cannot expand,” writes Larry Sabato, director of the Center for Politics at the University of Virginia, in an e-mail to the Monitor. “Some Romney backers have gone as far to say privately [to me and others] that a Paul win in Iowa is almost as good as a Romney victory.”

Iowa’s fractured conservative vote – most recently gravitating toward Rick Santorum – is also a boon for Romney. Add that to how Mr. Paul draws voters who aren’t keen on mainstream Republican positions and candidates. So, with about 25 percent of the vote, “Romney ... could end up finishing second or maybe even winning” in Iowa, says John Geer, a political science professor at Vanderbilt University in Nashville, Tenn.

If Mr. Santorum somehow pulls off an Iowa win, he would get a surge of attention. But he would then have to go through a vetting process that Romney has already been through, and Santorum has less money and organization than Romney, Professor Geer notes.

In four recent polls of likely caucusgoers in Iowa, Romney and Paul have been in first or second place, averaging about 21 or 22 percent support, according to the RealClearPolitics tracker.

Romney is currently smiling his way through a three-day bus tour in Iowa, courting votes but trying to avoid building up expectations too high. He’s zipping back to New Hampshire Friday evening for a spaghetti dinner at the Merrimack VFW.

A strong win in the Granite State is widely viewed as essential for the Romney campaign.

Romney has 44 percent support among likely primary voters in New Hampshire, followed by Paul at 17 percent, Newt Gingrich at 16 percent, and Jon Huntsman Jr. at 9 percent, according to the most recent poll, by CNN/Time.

“Ron Paul and Mitt Romney are drawing from two different parts of the Republican electorate” in New Hampshire, says Dante Scala, a political science professor at the University of New Hampshire in Durham.

While Romney draws from the mainstream, Paul draws from the outskirts – libertarians, moderate liberal Republicans, and independents. If Paul has a surge because of Iowa, Professor Scala adds, “the one person that hurts is Huntsman ... who is drawing from a similar pool [as Paul’s].”

Mr. Huntsman took on both opponents earlier this week during his 129th campaign event in the state, in Pelham, N.H. The two represent a choice of “what the establishment is telling you to do ... the status quo candidate [Romney],” or Paul, who’s “not electable at the end of the day,” Huntsman said, according to SalemPatch.com.

The conservative Union Leader newspaper in Manchester, N.H., editorialized Thursday that Paul “is a dangerous man,” criticizing his views on Iran’s apparent pursuit of nuclear weapons, among other things. “It’s about time New Hampshire voters showed him the door,” publisher Joseph McQuaid wrote.

With Paul taking hits from so many others, Romney has been able to remain magnanimous. Asked by CNN’s Wolf Blitzer if he would vote for Paul if he were the GOP nominee, Romney didn’t hesitate to say yes: Despite his disagreements with Paul, he would be better than Barack Obama, Romney said. Mr. Gingrich and Huntsman both avoided a direct answer to similar questions this week.

“Romney wants to look presidential ... and for the most part, he’s tried to stay above [the fray],” Geer says. “At the end of the day, you are still going to want ... the backing of [some Paul supporters] ... [so] you don’t want to leave any bad feelings,” he adds.

Paul’s backers are fervent, but his level of support has remained pretty steady rather than attracting many new converts, says Samuel Clovis, a professor at Morningside College in Sioux City, Iowa, and host of a conservative radio talk show. Professor Clovis recently criticized Paul’s foreign-policy stances and endorsed Santorum, but he credits Romney for high-quality interactions with voters in Iowa.

Some pundits, however, say the strength of Paul’s support as a type of protest vote may be underestimated. There’s still speculation that Paul might eventually mount an independent run for the presidency.

In an opinion piece in Thursday’s Wall Street Journal, Daniel Henninger writes: “... the Paul vote won’t die.... The Romney campaign may assume that this vote must land by default in their man’s lap ... [but] this is one of the most volatile Republican electorates in a long while.... [If Romney] doesn’t reach out pretty soon to the Paul-[Rick] Perry-[Michele] Bachmann Republican protest voters, he may never get them.”